<template>
    <transition name="fade">
        <div class="lg-preview-wrapper" v-show="preview.show" @click="leave" @touchmove.prevent>
            <div class="lg-preview-loading" v-show="preview.loading"><div></div></div>
            <img
                class="lg-preview-img"
                v-if="preview.current.src"
                :src="preview.current.src"
                :alt="preview.current.title"
                v-show="!preview.loading"
            >
            <div class="lg-preview-title" v-if="preview.isTitleEnable&&preview.current.title" v-show="!preview.loading">
                {{preview.current.title}}
            </div>
            <div class="lg-preview-nav-left" v-if="preview.isHorizontalNavEnable" v-show="!preview.loading">
                <span class="lg-preview-nav-arrow" @click="preAction" ></span>
            </div>
            <div class="lg-preview-nav-right" v-if="preview.isHorizontalNavEnable" v-show="!preview.loading">
                <span class="lg-preview-nav-arrow" @click="nextAction"></span>
            </div>
        </div>
    </transition>
</template>

<script>
export default {
    name: 'Preview',
    computed: {
        preview () {
            return window.LOGIC_EVENT_BUS.LOGIC_PREVIEW
        }
    },
    methods: {
        leave (e) {
            if ((this.preview.show)&&(e.target.className.indexOf('lg-preview-nav-arrow') != 0)){
               this.close()
            }
        },
        close () {
            this.preview.show = false
        },
        preAction () {
            this.preview.loading = true
            var index = this.preview.list.indexOf(this.preview.current)
            if (index === 0) {
                this.preview.loading = false
                return
            }
            index--
            this.preview.current = this.preview.list[index]
            const img = new window.Image()
            img.src = this.preview.current.src
            img.onload = function () {
                setTimeout(function () {
                    LOGIC_EVENT_BUS.LOGIC_PREVIEW.loading = false
                },500)
            }
        },
        nextAction () {
            this.preview.loading = true
            var index = this.preview.list.indexOf(this.preview.current)
            if (index === this.preview.list.length - 1) {
                this.preview.loading = false
                return
            }
            index++
            this.preview.current = this.preview.list[index]
            const img = new window.Image()
            img.src = this.preview.current.src
            img.onload = function () {
                setTimeout(function () {
                    LOGIC_EVENT_BUS.LOGIC_PREVIEW.loading = false
                },500)
            }
        },
    }
}
</script>

<style scoped>
.fade-enter-active, .fade-leave-active {
    transition: opacity .5s
}

.fade-enter, .fade-leave-active {
    opacity: 0
}

.lg-preview-wrapper {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    text-align: center;
    box-sizing: border-box;
    background: rgba(0, 0, 0, 0.9);
    z-index: 10000;
}

.lg-preview-loading {
    position: absolute;
    width: 30px;
    height: 35px;
    top: 50%;
    left: 50%;
    margin-top: -17.5px;
    margin-left: -15px;
}

.lg-preview-loading > div {
    display: inline-block;
    height: 25px;
    width: 25px;
    background: transparent;
    border-radius: 100%;
    border: 2px solid #fff;
    border-bottom-color: transparent;
    -webkit-animation-fill-mode: both;
    animation-fill-mode: both;
    -webkit-animation: rotate 0.75s 0s linear infinite;
    animation: rotate 0.75s 0s linear infinite;
}

@keyframes rotate {
    0% {
        -webkit-transform: rotate(0deg) scale(1);
        transform: rotate(0deg) scale(1);
    }

    50% {
        -webkit-transform: rotate(180deg) scale(0.6);
        transform: rotate(180deg) scale(0.6);
    }

    100% {
        -webkit-transform: rotate(360deg) scale(1);
        transform: rotate(360deg) scale(1);
    }
}

.lg-preview-img {
    max-width: 100%;
    max-height: 100%;
    display: block;
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    right: 0;
    margin: auto;
}

.lg-preview-nav-arrow {
    position: absolute;
    top: 50%;
    margin-top: -15px;
    background: rgba(0, 0, 0, 0);
    line-height: 40px;
    width: 20px;
    height: 20px;
    border-top: 2px solid #fff;
    border-left: 2px solid #fff;

}

.lg-preview-nav-left,
.lg-preview-nav-right {
    position: absolute;
    height: 100%;
    margin: 0 5px;
    width: 200px;
    top: 0;
    color: #fff;
    transition: opacity .2s;
}

.lg-preview-nav-left {
    left: 0;
}

.lg-preview-nav-left .lg-preview-nav-arrow {
    left: 0;
    margin-left: 40px;
    transform: rotate(-45deg);
}

.lg-preview-nav-right {
    right: 0;
}

.lg-preview-nav-right .lg-preview-nav-arrow {
    right: 0;
    margin-right: 40px;
    transform: rotate(135deg);
}

.lg-preview-title {
    position: absolute;
    left: 0;
    bottom: 0;
    text-align: center;
    width: 100%;
    color: #fff;
    background: rgba(0, 0, 0, .5);
    box-sizing: border-box;
    font-size: 16px;
    height: 40px;
    line-height: 40px;
}

@media all and (max-width: 768px) {
    .lg-preview-nav-left,
    .lg-preview-nav-right {
        width: 100px;
    }

    .lg-preview-nav-left .lg-preview-nav-arrow {
        margin-left: 20px;
    }

    .lg-preview-nav-right .lg-preview-nav-arrow {
        margin-right: 20px;
    }
}
</style>
